大变倍比中波红外连续变焦光学系统设计

Design of MWIR continuous zoom optical system with large zoom range

针对中波制冷型640×512凝视焦平面探测器,设计了一个大变倍比中波红外连续变焦光学系统。该系统采用三次成像技术,其工作波段为3.7~4.8μm,F数为4,变倍比为30：1,可实现23~701mm连续变焦,变焦轨迹平滑,满足100%冷光阑效率。该系统采用硅、锗和硒化锌三种红外材料,通过引入非球面和衍射面来校正系统的轴外像差和高级像差。系统在30 lp/mm处,全焦距范围内调制传递函数（MTF）均在0.15以上,接近衍射极限。设计结果表明,大变倍比中波红外连续变焦光学系统具有变倍比大、分辨率高、结构紧凑、像质好等优点。

For medium wave cool 640 ×512 detector wit h staring focal plane array,a MWIR continuous zoom optical system with large zoom range was designed.The optical system imaged thrice.The operating wavelength range was 3.7-4.8 μm,F number was 4 and the zoom ratio was 30：1.The optical system could realize 23-701 mm continuous zoom and meet 100% cold shield efficiency with smooth zoom locus.Three infrared materials of Si,Ge and ZnSe were used in the optical system.The system could correct the off axis aberration and higher order aberration by leading the aspheric surface and the diffractive surface.The MTF was above 0.15 within the whole focal range at the spatial frequency of 30 lp/mm and it approached the diffraction limit.The results show that the MWIR continuous zoom optical system has large zoom ratio,high resolution,small volume and excellent image quality.